Problem: $3ef - 3eg - 5e - 5 = -10f - 10$ Solve for $e$.
Solution: Combine constant terms on the right. $3ef - 3eg - 5e - {5} = -10f - {10}$ $3ef - 3eg - 5e = -10f - {5}$ Notice that all the terms on the left-hand side of the equation have $e$ in them. $3{e}f - 3{e}g - 5{e} = -10f - 5$ Factor out the $e$ ${e} \cdot \left( 3f - 3g - 5 \right) = -10f - 5$ Isolate the $e$ $e \cdot \left( {3f - 3g - 5} \right) = -10f - 5$ $e = \dfrac{ -10f - 5 }{ {3f - 3g - 5} }$ We can simplify this by multiplying the top and bottom by $-1$. $e= \dfrac{10f + 5}{-3f + 3g + 5}$